Multilayer inductor component and method for manufacturing multilayer inductor component

ABSTRACT

A multilayer inductor component includes an element body that is an insulator and a coil in which a plurality of coil conductor layers that extend along planes in the element body are electrically connected to each other. Also, each of the coil conductor layers includes metal part and glass part, and the glass part include internal glass portion that is entirely included in the metal part.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.17/732,430, filed Apr. 28, 2022, which is a Continuation of U.S. patentapplication Ser. No. 16/205,045, filed Nov. 29, 2018, which claimsbenefit of priority to Japanese Patent Application No. 2017-240997,filed Dec. 15, 2017, the entire content of which is incorporated hereinby reference.

BACKGROUND Technical Field

The present disclosure relates to a multilayer inductor component formedby stacking insulator layers and coil conductor layers, and to a methodfor manufacturing a multilayer inductor component.

Background Art

In recent years, in accordance with increases in carrier frequencies ofcommunication devices, e.g., cellular phones, many coiled inductorscompatible with high frequencies in a GHz band have been used in signalsending blocks and signal receiving blocks of these devices. Amultilayer inductor component has been in actual use as one type of suchan inductor. The multilayer inductor component includes an element bodythat is an insulator and a plurality of coil conductor layers thatextend along planes in the element body, and a coil is formed in theelement body by electrically connecting the coil conductor layers toeach other by using vias disposed in the element body. The coilconductor layer is formed by, for example, firing a conducting paste inwhich a metal is contained in a resin or performing sputtering, plating,or the like.

Regarding the above-described multilayer inductor component, it isnecessary to ensure a high Q-factor (quality factor) in order to improvethe performance of communication devices that operate at high frequency.For the purpose of increasing the Q-factor, it is required to reduce theresistance of a coil or to increase the efficiency of inductance thatcan be acquired with respect to the element body external shape(inductance acquisition efficiency).

A high-frequency current that passes through a coil conductor layerpasses in the vicinity of the surface of the coil conductor layerbecause of a skin effect. Therefore, in order to reduce the resistanceof the coil against a high-frequency current, it is effective toincrease the surface area of the coil conductor layer.

Japanese Unexamined Patent Application Publication No. 2014-45081discloses a multilayer inductor component in which the resistance of acoil is reduced by increasing the surface area of a coil conductor layerdue to porosities that are formed in a conductive paste by a metalsintering around a resin before the resin is scattered because ofgasification during firing.

SUMMARY

FIGS. 11A and 11B show the multilayer inductor component disclosed inJapanese Unexamined Patent Application Publication No. 2014-45081.Regarding the inductor component 1, the resistance of a coil is reducedby increasing the surface area of a coil conductor layer 2 due toporosities that are formed in the coil conductor layer 2 (coilconductor).

Meanwhile, the gasification temperature of a resin in a conductive pasteis usually lower than the sintering completion temperature of a metalpowder that is a primary component of the conductive paste and,therefore, porosities 3 formed after firing are not readily includedentirely in a metal part of the coil conductor layer 2.

The material, for example, a glass powder, for forming the element body4 covering the coil conductor layer 2 is sintered faster than the metalpowder. Therefore, gas generated in the conductive paste is not readilyscattered outside the element body 4 and is readily retained in thevicinity of the peripheral edge of the coil conductor layer 2, andporosities 3 are readily formed in that region.

In the thus formed multilayer inductor component 1 in practice, theperipheral edge of the coil conductor layer 2 do not have a smooth shapeshown in FIG. 11A or FIG. 11B but has significant unevenness due toporosities 3 generated in the vicinity of the peripheral edge. In thecoil conductor layer 2 having such a shape, smooth flow of a current ishindered, loss due to, for example, generation of an eddy current causedby local concentration of a current or disturbance in the direction ofmagnetic flux increase, and the inductance acquisition efficiency isreduced. Porosities 3 formed in the vicinity of the peripheral edge ofthe coil conductor layer 2 reduce the strength of the coil conductorlayer 2 and may become a cause of an occurrence of breakage or anincrease in resistance of the coil. That is, if the resistance of thecoil is reduced by using the porosities 3 in the coil conductor layer 2,as disclosed in Japanese Unexamined Patent Application Publication No.2014-45081, various problems may occur.

The present disclosure was realized in consideration of theabove-described circumstances. Accordingly, the present disclosureprovides a multilayer inductor component in which the resistance of acoil can be reduced without using porosities.

According to one embodiment of the present disclosure, a multilayerinductor component includes an element body that is an insulator and acoil in which a plurality of coil conductor layers that extend alongplanes in the element body are electrically connected to each other.Also, each of the coil conductor layers includes a metal part and aglass part, and the glass part include an internal glass portion that isentirely included in the metal part.

In this configuration, the surface area of the coil conductor layer isincreased by the internal glass portion. In the above-describedmultilayer inductor component, preferably, the glass part include anexposed glass portion that is exposed from the metal part, and the coilconductor layer has a cross section orthogonal to an extension directionof the coil conductor layer in which the proportion of an total area ofthe internal glass portion to an area of the glass part is less thanabout 50%.

In this configuration, the surface area of the coil conductor layer isalso increased by the exposed glass portion. In the above-describedmultilayer inductor component, preferably, the coil conductor layer hasa cross section orthogonal to an extension direction of the coilconductor layer in which the proportion of a total area of the internalglass portion to an area of the glass part is about 50% or more.

In this configuration, the surface area of the coil conductor layer isincreased and, in addition, smoothing of the peripheral edges of themetal part in the coil conductor layer is facilitated. In theabove-described multilayer inductor component, preferably, to coilconductor layer has a cross section orthogonal to the extensiondirection in which the proportion of a total area of the internal glassportion to an area of the glass part is 100%.

In this configuration, smoothing of the peripheral edges of the metalpart in the coil conductor layer is further facilitated. In theabove-described multilayer inductor component, preferably, the coilconductor layer has a cross section orthogonal to the extensiondirection in which the proportion of an total area of the internal glassportion to an area of the coil conductor layer is about 1.0% or more and20.0% or less (i.e., from about 1.0% to about 20.0%).

In this configuration, a smooth flow of current in the coil conductorlayer is facilitated and, in addition, the surface area of the coilconductor layer can be increased. In the above-described multilayerinductor component, preferably, the element body includes glass, andwhen a glass portion in the element body within about 10 μm from theperimeter of the coil conductor layer is denoted as a peripheral glassportion and a glass portion in the element body outside the peripheralglass portion is denoted as an outlying glass portion, the softeningtemperature of the peripheral glass portion is lower than the softeningtemperature of the outlying glass portion.

In this configuration, the coil conductor layer is formed in the stateof being surrounded by the peripheral glass portion that is relativelyreadily softened and, therefore, smoothing of the peripheral edge of thecoil conductor layer is facilitated. In the above-described multilayerinductor component, preferably, the softening temperature of theperipheral glass portion is lower than or equal to the softeningtemperature of the internal glass portion.

In this configuration, the coil conductor layer is formed in the stateof being surrounded by the peripheral glass portion that is relativelyreadily softened and, therefore, smoothing of the peripheral edge of thecoil conductor layer is facilitated. In the above-described multilayerinductor component, preferably, the element body includes glass, andwhen a glass portion in the element body within about 10 μm from theperimeter of the coil conductor layer is denoted as a peripheral glassportion and a glass portion in the element body outside the peripheralglass portion is denoted as an outlying glass portion, the peripheralglass portion contains at least one type of filler element that is anyone of Bi, Li, Na, K, Mg, Ca, Sr, Ba, Co, Zn, B, Pb, Al, Zr, P, and V,and the peripheral glass portion has a higher filler elementconcentration than the outlying glass portion.

In this configuration, the coil conductor layer is formed in the stateof being surrounded by the peripheral glass portion that is relativelyreadily softened and, therefore, smoothing of the peripheral edge of thecoil conductor layer is facilitated. In the above-described multilayerinductor component, preferably, the Si concentration in the peripheralglass portion is lower than the Si concentration in the outlying glassportion.

In this configuration, the coil conductor layer is formed in the stateof being surrounded by the peripheral glass portion that is relativelyreadily softened and, therefore, smoothing of the peripheral edge of thecoil conductor layer is facilitated. In the above-described multilayerinductor component, preferably, when a glass portion located at anoutermost position in a direction orthogonal to the plane along whichthe coil conductor layer in the element body extends is denoted as anouter layer glass portion, the Si concentration in the peripheral glassportion is lower than the Si concentration in the outer layer glassportion.

In this configuration, the clarity of the portion located at anoutermost position in the element body is improved, the visibility of analignment mark is improved, and precision in division into pieces isimproved. In the above-described multilayer inductor component,preferably, when a glass portion located at an outermost position in adirection orthogonal to the plane along which the coil conductor layerin the element body extends is denoted as an outer layer glass portion,the Si concentration in the peripheral glass portion is higher than theSi concentration in the outer layer glass portion.

In this configuration, the strength of the element body is enhanced. Inthe above-described multilayer inductor component, preferably, the metalpart has a plurality of crystallites, and the average grain size of theplurality of crystallites is about 0.5 μm or more and 15.0 μm or less(i.e., from about 0.5 μm to 15.0 μm).

In this configuration, grain boundaries that suppress the flow ofelectrons are decreased. Therefore, the resistance of the coil conductorlayer can be reduced, excessive growth of crystallites is suppressed,and smoothing of the peripheral edge of the coil conductor layer isfacilitated.

In the above-described multilayer inductor component, preferably, theelement body is a sintered body. In this configuration, the strength ofthe element body is enhanced.

In the above-described multilayer inductor component, preferably, afirst outer electrode and a second outer electrode that are disposedalong an outer surface of the element body and that are electricallyconnected to a first end and a second end of the coil, respectively, arefurther included. The outer surface includes a mounting surface on whichboth the first outer electrode and the second outer electrode aredisposed, a first end surface on which only the first outer electrode isdisposed, and a second end surface on which only the second outerelectrode is disposed. Also, the mounting surface, the first endsurface, and the second end surface are orthogonal to the planes alongwhich the coil conductor layers extend.

In this configuration, the fixing force during mounting on a substrateis increased and, in addition, reduction in Q-factor due to eddy currentloss is suppressed. According to another embodiment of the presentdisclosure, a multilayer inductor component includes an element bodythat is an insulator and a coil in which a plurality of coil conductorlayers that extend along planes in the element body are electricallyconnected to each other. Each of the coil conductor layers includes ametal part and a glass part. The element body includes glass, and when aglass portion in the element body within about 10 μm from the perimeterof the coil conductor layer is denoted as a peripheral glass portion anda glass portion in the element body outside the peripheral glass portionis denoted as an outlying glass portion, the softening temperature ofthe peripheral glass portion is lower than the softening temperature ofthe outlying glass portion.

In this configuration, the coil conductor layer is formed in the stateof being surrounded by the peripheral glass portion that is relativelyreadily softened and, therefore, smoothing of the peripheral edge of thecoil conductor layer is facilitated. In the above-described multilayerinductor component, preferably, the softening temperature of theperipheral glass portion is lower than or equal to the softeningtemperature of the glass part.

In this configuration, the coil conductor layer is formed in the stateof being surrounded by the peripheral glass portion that is relativelyreadily softened and, therefore, smoothing of the peripheral edge of thecoil conductor layer is facilitated. According to another embodiment ofthe present disclosure, a method for manufacturing a multilayer inductorcomponent includes the steps of forming a multilayer body by using aninsulating paste containing a glass powder and an conductive pastecontaining a metal powder and a glass powder such that coil conductorpatterns composed of the conductive paste are arranged between aplurality of insulating paste layers composed of the insulating paste inthe multilayer body and firing the multilayer body so as to sinter themetal powder and the glass powder into a metal part and a glass part,respectively. In the forming a multilayer body, the glass powdercontained in the conductive paste has a lower softening temperature thanthe glass powder contained in the insulating paste. In the firing of themultilayer body, the glass powder contained in the conductive pasteforms an internal glass portion by entirely included into the metal partand sintered, and the glass powder contained in the conductive pasteforms a peripheral glass portion by pushed outside the metal part andsintered.

In this method, regarding coil conductor layer formed by sintering thecoil conductor pattern, the surface area is increased and smoothing ofthe peripheral edge is facilitated due to the internal glass portion andthe peripheral glass portion formed in the firing of the multilayerbody.

In the multilayer inductor component according to some embodiments ofthe present disclosure, the resistance of a coil can be reduced withoutusing porosities.

Other features, elements, characteristics and advantages of the presentdisclosure will become more apparent from the following detaileddescription with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a multilayer inductor component;

FIG. 2 is an exploded perspective view showing an outline of eachportion of a multilayer inductor component;

FIGS. 3A to 3D are explanatory diagrams showing a firing process of acoil conductor;

FIGS. 4A to 4D are explanatory diagrams showing a firing process of acoil conductor;

FIGS. 5A to 5D are explanatory diagrams showing a firing process of acoil conductor;

FIG. 6 is a schematic diagram showing a coil conductor in a firing step;

FIG. 7 is an explanatory diagram showing a method for calculating thediameter of a crystallite in a coil conductor;

FIG. 8 is a schematic diagram showing a coil conductor in a firing step;

FIG. 9 is a schematic sectional view showing a multilayer body afterfiring;

FIG. 10 is a schematic plan view showing a multilayer body after firing;and

FIGS. 11A and 11B are sectional views showing multilayer coil componentsin the related art.

DETAILED DESCRIPTION

The embodiment according to an aspect of the present disclosure will bedescribed below with reference to the drawings. A multilayer inductorcomponent 10 shown in FIG. 1 includes an element body 11 that is aninsulator, a coil 12 disposed in the element body 11, and a first outerelectrode 13 x and a second outer electrode 13 y that are disposed alongthe outer surfaces of the element body 11 and that are electricallyconnected to a first end and a second end, respectively, of the coil 12.

The element body 11 is formed by stacking a plurality of insulatinglayers, and the coil 12 is formed by electrically connecting a pluralityof coil conductor layers that extend along planes corresponding to theprincipal surfaces of the insulating layers in the element body 11 toeach other by using vias 14. The outer surfaces of the element body 11include a mounting surface 11 a on which both the first outer electrode13 x and the second outer electrode 13 y are disposed, a first endsurface 11 b on which only the first outer electrode 13 x is disposed,and a second end surface 11 c on which only the second outer electrode13 y is disposed, and the mounting surface 11 a, the first end surface11 b, and the second end surface 11 c are orthogonal to the principalsurface of the insulating layer. That is, in the multilayer inductorcomponent 10 shown in FIG. 1 , the mounting surface 11 a, the stackingdirection of the insulating layers, and the winding axis of the coil 12are parallel to each other.

FIG. 2 shows an outline of each portion of a multilayer inductorcomponent 10. Insulating layers 15 a, 15 b, 16 a to 16 c, and 18constituting the element body 11, coil conductor layers 12 a to 12 cconstituting the coil 12, and outer electrode layers 13 a to 13 econstituting the first outer electrode 13 x and the second outerelectrode 13 y are stacked sequentially, for example, from the bottomtoward the top in FIG. 2 . In FIG. 1 , stacking is performed, forexample, from the front surface toward the back surface of the elementbody 11. In this regard, the stacking direction may be the directionopposite to the direction shown in FIG. 1 or FIG. 2 .

An example of a method for manufacturing the multilayer inductorcomponent 10 will be described below with reference to FIG. 2 .Initially, an insulating paste containing a glass powder is repeatedlyapplied to a substrate, although not shown in the drawing, by screenprinting so as to form a marker insulating paste layer 18 and outerlayer insulating paste layers 15 a in this order. Subsequently, aphotosensitive conductive paste containing a metal powder and a glasspowder is applied to the outer layer insulating paste layer 15 a andpatterning is performed by photolithography so as to form a pair ofouter electrode patterns 13 a.

One outer electrode pattern 13 a is formed into the shape of a letter Lfrom the position corresponding to the mounting surface 11 a to theposition corresponding to the first end surface 11 b of the outer layerinsulating paste layer 15 a, and the other outer electrode pattern 13 ais formed into the shape of a letter L from the position correspondingto the mounting surface 11 a to the position corresponding to the secondend surface 11 c of the outer layer insulating paste layer 15 a. Aphotosensitive insulating paste containing a glass powder is applied tothe outer layer insulating paste layer 15 a provided with the outerelectrode patterns 13 a, and patterning is performed by photolithographyso as to form an insulating paste layer 16 a provided with cavities 17on the outer electrode patterns 13 a.

The above-described conductive paste is applied to the insulating pastelayer 16 a and the cavities 17, and patterning is performed byphotolithography so as to form a pair of outer electrode patterns 13 band a coil conductor pattern 12 a that extends and makes about one roundon the principal surface of the insulating paste layer 16 a. The coilconductor pattern 12 a is integrally formed with one of the outerelectrode patterns 13 b so as to be electrically connected to eachother. Each of the outer electrode patterns 13 b is stacked on andelectrically connected to the outer electrode pattern 13 a through thecavity 17.

The above-described photosensitive insulating paste is applied to theinsulating paste layer 16 a provided with the outer electrode pattern 13b and the coil conductor pattern 12 a, and patterning is performed byphotolithography so as to form an insulating paste layer 16 b providedwith a via 14 and the same cavity 17 as that in the insulating pastelayer 16 a. The via 14 is formed on the end portion that is notconnected to the outer electrode pattern 13 b of the coil conductorpattern 12 a.

The above-described conductive paste is applied to the insulating pastelayer 16 b, the cavities 17, and the via 14, and patterning is performedby photolithography so as to form a pair of outer electrode patterns 13c and a coil conductor pattern 12 b that extends and makes about oneround on the principal surface of the insulating paste layer 16 b. Oneend portion of the coil conductor pattern 12 b is electrically connectedto the coil conductor pattern 12 a that is a layer under the coilconductor pattern 12 b through the conductive paste applied into the via14. Each of the outer electrode patterns 13 c is stacked on andelectrically connected to the outer electrode pattern 13 b through thecavity 17.

The same steps as those described above are appropriately combined andrepeated and, thereby, a plurality of insulating paste layers 16 a to 16d and coil conductor patterns 12 a to 12 c connected to each otherthrough the cavities 17 are stacked. The coil conductor pattern 12 cserving as the uppermost layer is integrally formed with one of theouter electrode patterns 13 d at the end portion opposite to the via 14so as to be electrically connected to each other.

The insulating paste is applied to the insulating paste layer 16 dprovided with the outer electrode patterns 13 e so as to form the outerlayer insulating paste layers 15 b and the marker insulating paste layer18 in this order. Consequently, a multilayer body is formed.

A plurality of multilayer inductor components 10 shown in FIG. 2 may besimultaneously formed. In this case, a mother multilayer body in which aplurality of outer electrode patterns 13 a to 13 e and coil conductorpatterns 12 a to 12 c are arranged in a matrix may be formed, and themother multilayer body may be cut into the individual multilayer bodiesby dicing. At this time, as shown in FIG. 1 , the outer electrodepatterns 13 a to 13 e are exposed at the surfaces corresponding to themounting surface 11 a, the first end surface 11 b, and the second endsurface 11 c of the multilayer body. In this case, the outer electrodepatterns 13 a to 13 e and the cavities 17 may be formed into the shapeof a letter T or a cross instead of the shape of a letter L and formedinto the shape of a letter L by dicing.

Subsequently, the multilayer body is fired under a predeterminedcondition and, thereby, the insulating paste layers, coil conductorpatterns, and the outer electrode patterns are sintered so as to formthe insulator layers, the coil conductor layers, and outer electrodelayers. Then, barrel finishing is performed so as to form the elementbody 11, the coil 12, and the outer electrodes 13 x and 13 y shown inFIG. 1 . Thereafter, the outer electrodes 13 x and 13 y are subjected toNi plating and Sn plating having a thickness of about 2 μm to 10 μm inthis order so as to complete the multilayer inductor component 10.

In the above description, the insulating paste serving as a material forforming the outer layer insulating paste layers 15 a and 15 b, theinsulating paste layers 16 a to 16 d, and the marker insulating pastelayer 18 is, for example, a glass paste in which a glass powder isincluded in a varnish. In this regard, the insulating paste serving as amaterial for forming the outer layer insulating paste layers 15 a and 15b and the marker insulating paste layer 18 may be either photosensitiveor non-photosensitive. The insulating paste serving as a material forforming the marker insulating paste layer 18 may contain a pigment, andthe surfaces of the multilayer inductor component 10 can be therebydistinguished.

The photosensitive conductive paste for forming the coil conductorpatterns 12 a to 12 c and outer electrode patterns 13 a to 13 e is, forexample, a paste in which a metal powder of Ag, Cu, Au, or the like anda glass powder are included in a varnish. The glass powder included inthe insulating paste or the conductive paste may contain Bi, Li, Na, K,Mg, Ca, Sr, Ba, Co, Zn, B, Pb, Al, Zr, P, V, and the like.

Next, the configuration of the coil conductor layers 12 a to 12 c inwhich the conductive paste containing the above-described metal powderand glass powder is sintered in the firing step will be described. FIGS.3A to 3D show the configuration of the coil conductor layers 12 a to 12c that is sintered at a sintering temperature of t1, t2, or t3 for afiring time of T1 or T2 with reference to a section (cross section)orthogonal to the extension direction of the coil conductor layers 12 ato 12 c.

Regarding the firing temperatures t1 to t3, t1<t2<t3 applies, andregarding the firing times T1 and T2, T1<T2 applies. That is, when thefiring step is finished, the degree of advance in sintering of the coilconductor layers 12 a to 12 c with respect to FIG. 3B is higher than thedegree with respect to FIG. 3A, the degree with respect to FIG. 3C ishigher than the degree with respect to FIG. 3B, and the degree withrespect to FIG. 3D is higher than the degree with respect to FIG. 3B.

As shown in FIGS. 3A to 3D, each of the coil conductor layers 12 a to 12c includes a metal part M in which a metal powder contained in theconductive paste is sintered and a glass part GLA in which a glasspowder is sintered. The glass part GLA include internal glass portionsGLAi each entirely included in the metal part M and exposed glassportions GLAo exposed from and partially included in the metal part M.

The element body 11 includes a peripheral glass portion GLB as a glassportion in the element body 11 within 10 μm from the perimeter of eachof the coil conductor layers 12 a to 12 c. As is clear from FIG. 3A andFIG. 3B in which sintering does not much advance, the glass part GLAincludes not only the internal glass portions GLAi but also the exposedglass portions GLAo. On the other hand, as is clear from FIG. 3C andFIG. 3D in which sintering advances, the glass part GLA do not includethe exposed glass portions GLAo but include only the internal glassportions GLAi. Also, it is shown that the peripheral edges of the metalpart M become smoother in proportion to the degree of advance insintering.

The sintering process of the coil conductor layers 12 a to 12 c will bedescribed in detail with reference to the schematic diagram shown inFIGS. 5A to 5D. As shown in FIG. 5A, the coil conductor patterns 12 a to12 c before firing are photo-cured photosensitive conductive pastes andare in the state in which the metal powder M and the glass powder GLAare dispersed in a varnish 19 serving as a binder.

When sintering is started in this state, as shown in FIG. 5B, burningand scattering of the varnish 19 advance, the metal powder M is sinteredso as to become the metal part M and, in addition, necking occurs so asto increase the interfaces between adjacent metal part M. At this time,the glass powder GLA is also sintered so as to become the glass partGLA. However, some glass part GLA having relatively low softeningtemperatures are softened and begin to flow along the interfaces betweenmetal part M.

Subsequently, as shown in FIG. 5C, sintering of metal part M is furtherfacilitated because softened glass part GLA flow along the interfacesbetween metal part M, and grain sizes of metal part M increase. At thistime, internal glass portions GLAi that are entirely included in themetal part M and sintered because the softening temperature isrelatively high and the amount of flow is small and exposed glassportions GLAo that flows and sinters at peripheral edges of the metalpart M because the softening temperature is relatively low. Some glasspart GLA that are softened and flow in advance of the exposed glassportions GLAo are pushed outside the metal part M and sintered so as toform the peripheral glass portions GLB of the element body 11.Therefore, at this stage, the coil conductor layers 12 a to 12 c thatinclude the metal part M and the glass part GLA shown in FIG. 3A andFIG. 3B, the glass part GLA including the internal glass portions GLAiand the exposed glass portions GLAo, are formed. At this time, the coilconductor layers 12 a to 12 c are formed in the state of being partlysurrounded by the peripheral glass portion GLB that is softened inadvance. Consequently, smoothing of the peripheral edges composed of themetal part M and the exposed glass portions GLAo of the coil conductorlayers 12 a to 12 c is facilitated.

As shown in FIG. 5D, when firing further advances, the grain sizes ofthe metal part M further increases, and the exposed glass portions GLAois pushed outside the metal part M so as to become the peripheral glassportion GLB. consequently, at this stage, the coil conductor layers 12 ato 12 c that include the metal part M and the glass part GLA, the glasspart GLA including only the internal glass portions GLAi, shown in FIG.3C and FIG. 3D are formed. At this time, the coil conductor layers 12 ato 12 c are formed in the state in which the exposed glass portions GLAoare pushed outside the metal part M and, therefore, the peripheral edgesof the metal part M in the coil conductor layers 12 a to 12 c are madesmooth.

As described above, the proportion of the internal glass portions GLAiin the glass part GLA can be controlled by the amount of the exposedglass portions GLAo pushed out (converted to the peripheral glassportion GLB), that is, the degree of advance of sintering.

FIGS. 4A to 4D show the configuration of the coil conductor layers 12 ato 12 c that is sintered at a firing temperature of t1, t2, or t3 for afiring time of T1 or T2 when Bi is added to the glass powder in theconductive paste for forming the coil conductor layers 12 a to 12 c.When Bi is added, the temperature at which the glass part formed bysintering the glass powder are softened (softening temperature) is lowerthan the softening temperature of the glass part formed by sintering aglass powder not including Bi.

As is clear from the result of comparisons between FIGS. 4A to 4D andFIGS. 3A to 3D with respect to the same firing temperature and the samefiring time, sintering of the coil conductor layers 12 a to 12 c inFIGS. 4A to 4D readily advances compared with the coil conductor layers12 a to 12 c in FIGS. 3A to 3D, the proportion of the internal glassportions GLAi to the glass part GLA is larger, and smoothing of theperipheral edges of the coil conductor layers 12 a to 12 c isfacilitated. As described above, the proportion of the internal glassportions GLAi in the glass part GLA can also be adjusted by addition orno addition of Bi to the glass powder. The degree of decrease in thesoftening temperature of the glass part formed by sintering the glassfiber containing Bi is substantially in proportion to the amount of Biadded. Therefore, the above-described proportion of the internal glassportions can also be adjusted by the amount of Bi added to the glasspowder.

As is clear from the above description, the glass powder that iscontained in the coil conductor layers 12 a to 12 c and that does notbecome the internal glass portions GLAi but becomes the exposed glassportions GLAo or the peripheral glass portion GLB has a relatively lowsoftening temperature and high fluidity. Therefore, in the coilconductor layers 12 a to 12 c, the softening temperature of the exposedglass portions GLAo and the softening temperature of the peripheralglass portion GLB are lower than or equal to the softening temperatureof the internal glass portions GLAi. The softening temperature of theperipheral glass portion GLB is lower than or equal to the softeningtemperature of the exposed glass portions GLAo. That is, regarding thesoftening temperature, the peripheral glass portion GLB the exposedglass portions GLAo the internal glass portions GLAi applies. When aglass portion in the element body 11 outside the peripheral glassportion in, for example, the central portion and the outer edge portionof the element body 11 is denoted as an outlying glass portion, it ispreferable that the softening temperature of the peripheral glassportion GLB be lower than the softening temperature of the outlyingglass portion. In this case, the coil conductor layers 12 a to 12 c areformed in the state of being surrounded by the peripheral glass portionGLB that is relatively readily softened. Therefore, smoothing of theperipheral edges of the coil conductor layers 12 a to 12 c isfacilitated. In addition, the outlying glass portion that is relativelyhard to soften is included and, thereby, strength and shape stability ofthe element body 11 are improved.

The filler element that is added to the glass powder for the purpose ofdecreasing the softening temperature of the glass part is not limited toBi as long as the filler element is any one of Bi, Li, Na, K, Mg, Ca,Sr, Ba, Co, Zn, B, Pb, Al, Zr, P, and V. That is, preferably, theperipheral glass portion GLB contains at least one of theabove-described filler elements. At this time, it is preferable that theperipheral glass portion GLB have a higher filler element concentration(total value of the concentrations of the above-described fillerelements) than the outlying glass portion. When the glass powderincluded in the conductive paste for forming the coil conductor layers12 a to 12 c contains at least one of the above-described fillerelements, regarding the filler element concentration, the peripheralglass portion GLB≥the exposed glass portions GLAo the internal glassportions GLAi applies from the viewpoint of the softening temperature inthe firing process.

In this regard, as shown in FIG. 6 , if the softening temperature isdecreased in a region more than 10 μm away from the perimeters of thecoil conductor layers 12 a to 12 c, that is, in the outlying glassportion, is decreased, short circuit may occur between adjacent coilconductor layers 12 a to 12 c because of excessive flowing of the metalpart M. Therefore, it is preferable that the outlying glass portion donot contain the above-described filler element or the outlying glasshave a lower filler element concentration than the peripheral glassportion GLB.

As the filler element concentration in the glass increases, the Siconcentration in the glass decreases. Therefore, regarding the Siconcentration, the peripheral glass portion GLB<the outlying glassportion applies. In the multilayer inductor component 10, the metal partM included in the coil conductor layers 12 a to 12 c form a plurality ofcrystallites, and the average grain size of the crystallites ispreferably about 0.5 μm or more and 15.0 μm or less (from about 0.5 μmto 15.0 μm). When the above-described average grain size of thecrystallites is about 0.5 μm or more, grain boundaries that suppress theflow of current are decreased and, therefore, the resistance of the coil12 can be reduced. Meanwhile, when the above-described average grainsize of the crystallites is about 15.0 μm or less, excessive growth ofcrystallites is suppressed, and smoothing of the peripheral edges of thecoil conductor layers 12 a to 12 c is facilitated.

The average grain size of the crystallites is analyzed by orientationimaging microscopy (OIM) that is an image analyzer. When the measurementby OIM is difficult, analysis may be performed by adopting focused ionbeam (FIB) and scanning ion microscopy (SIM).

In the latter case, as shown in FIG. 7 , specifically, in across-sectional image of each of the coil conductor layers 12 a to 12 c,the area of a crystallite 20 of the metal portion M is calculated, thediameter d of a perfect circle having the same area as the area of thecrystallite 20 is calculated and denoted as a grain size, and theaverage grain size is calculated. In the calculation of the averagegrain size, for example, five cross-sectional images of each of the coilconductor layers 12 a to 12 c may be taken from a cross section thatpasses the central portion of the element body 11, and an arithmeticaverage of the grain sizes of crystallites 20 in each image may becalculated.

Regarding the method for measuring the softening temperature, a portionincluding each glass may be cut as a sample from the element body 11 orthe coil conductor layers 12 a to 12 c, and the molten state may beexamined by a high-temperature microscope. Specifically, the sample isheated in a vacuum by using near-infrared rays or the like while beingobserved by the high-temperature microscope, the softening state of thesample is examined, and the temperature of start of softening is denotedas the softening temperature.

FIG. 8 is a diagram showing the state in which a firing step of anexample of the multilayer inductor component 10 has been finished. InFIG. 8 , the concentration of the filler element included in the glassis expressed by shading, a light portion excluding the coil conductorlayer portion is a region in which the filler element concentration ishigh, and a dark portion is a region in which the filler elementconcentration is low. In the above-described example, an insulatingpaste including a glass powder and a conductive paste including a metalpowder and a glass powder were used, and a multilayer body in whichconductor patterns composed of the conductive paste were arrangedbetween a plurality of insulating paste layers composed of theinsulating paste was formed. In the above-described example, theabove-described multilayer body was fired in the firing step, and themetal powder and the glass powder were sintered into the metal part andthe glass part, respectively. Further, in the above-described example, aglass powder having a lower softening temperature than the glass powderincluded in the insulating paste was used as the glass powder includedin the conductive paste.

As is clear from FIG. 8 , in the step of firing the above-describedmultilayer body, each of internal glass portions GLAi in which the glasspowder included in the above-described conductive paste was entirelyincluded into the metal part and sintered (portion A in FIG. 8 ), aperipheral glass portion GLB in which the glass powder included in theabove-described conductive paste was pushed outside the metal part andsintered (portion B in FIG. 8 ), and an outlying glass portion in whichthe glass powder included in the above-described insulating paste wassintered (portion C in FIG. 8 ) were formed. Regarding the fillerelement concentration, it was found that the peripheral glass portionGLB>the outlying glass portion.

When a glass portion located at an outermost position in a directionorthogonal to the planes along which the coil conductor layers 12 a to12 c in the element body 11 extend (in the vertical direction in FIG. 9) is denoted as an outer layer glass portion, the glass portion includedin the insulator layers 18 (marker layers) serves as the outer layerglass portion in the multilayer inductor component 10. When the Siconcentration in the peripheral glass portion is lower than the Siconcentration in the outer layer glass portion, that is, when the fillerelement concentration in the outer glass portion is lower than thefiller element concentration in the peripheral glass portion, theclarity of the insulator layer 18 located at the outermost position inthe element body 11 is improved. At this time, as shown in FIG. 10 ,when alignment marks 21, which are used in division into pieces, areformed on the insulator layer 18 of a mother multilayer body, theclarity of the insulator layer 18 is improved, the visibility of thealignment marks 21 are improved, and precision in division into piecesis improved.

On the other hand, when the Si concentration in the peripheral glassportion is higher than the Si concentration in the outer layer glassportion, a filler that enhances the mechanical strength of the outerglass can be added so as to enhance the strength of the element body 11.

The multilayer inductor component having the above-describedconfiguration can exert the following effects.

(1) Each of the coil conductor layers 12 a to 12 c includes the metalpart M and the glass part GLA, and the glass part GLA include theinternal glass portion GLAi entirely included in the metal part M. Inthis configuration, the surface areas of the coil conductor layers 12 ato 12 c increase due to the internal glass portion GLAi. That is, theresistance of the coil 12 can be reduced without using porosities, andthe above-described various problems do not occur.

For example, in the multilayer inductor component 10, even when theinner diameters of the coil conductor layers 12 a to 12 c are increasedfor the purpose of improving the inductance acquisition efficiency andthe peripheral edges of the coil conductor layers 12 a to 12 c comeclose to the peripheral edge of the element body 11, reduction in thestrength of the element body 11 can be suppressed because the coilconductor layers 12 a to 12 c include no porosity.

(2) Preferably, the coil conductor layers 12 a to 12 c have a crosssection orthogonal to the extension direction of each of the coilconductor layers 12 a to 12 c in which the proportion of an total areaof the internal glass portions to an area of the glass part GLA is lessthan about 50%. In this configuration, the surface area of each of thecoil conductor layers 12 a to 12 c is increased by the exposed glassportions GLAo and, therefore, the resistance of the coil 12 can furtherbe reduced.

(3) Preferably, the coil conductor layers 12 a to 12 c have a crosssection orthogonal to the extension direction of each of the coilconductor layers 12 a to 12 c in which the proportion of an total areaof the internal glass portions to an area of the glass part GLA is about50% or more. In this configuration, the surface areas of each of thecoil conductor layers 12 a to 12 c is increased and, in addition,smoothing of the peripheral edges of the metal part M in each of thecoil conductor layers 12 a to 12 c is facilitated. Therefore, generationof eddy current due to nonuniformity in the direction of generation ofmagnetic flux in the central portion of the coil 12 is suppressed, andloss at high frequency can be reduced. In addition, reduction inmechanical strength of the coil 12 can be suppressed.

(4) Preferably, the coil conductor layers 12 a to 12 c have a crosssection orthogonal to the extension direction of each of the coilconductor layers 12 a to 12 c in which the proportion of a total area ofthe internal glass portions GLAi to an area of the glass part GLA is100%. In this configuration, smoothing of the peripheral edges of themetal part M in each of the coil conductor layers 12 a to 12 c isfurther facilitated.

(5) Preferably, the coil conductor layers 12 a to 12 c have a crosssection orthogonal to the extension direction of each of the coilconductor layers 12 a to 12 c in which the proportion of an total areaof the internal glass portions GLAi to an area of any of the coilconductor layers 12 a to 12 c is about 1.0% or more and 20.0% or less(i.e., from about 1.0% to 20.0%). In this configuration, when theproportion of an total area of the internal glass portions GLAi is about20.0% or less, a smooth flow of current in the coil conductor layers 12a to 12 c is facilitated. Meanwhile, when the proportion of a total areaof the internal glass portions GLAi is about 1.0% or more, the surfacearea of the coil conductor layers 12 a to 12 c can be increased. In thisregard, it is preferable that the above-described area ratio be realizedin a central cross section of the longest straight line portion of eachof the coil conductor layers 12 a to 12 c, and it is preferable that theabove-described area ratio be realized in a cross section of the coilconductor layer 12 a or coil conductor layer 12 c located at theoutermost position. In these configurations, the above-described effectsdue to the area ratio are most markedly exerted.

(6) Preferably, the softening temperature of the peripheral glassportion GLB is lower than the softening temperature of the outlyingglass portion. In this configuration, the coil conductor layers 12 a to12 c are formed in the state of being surrounded by the peripheral glassportion GLB that is relatively readily softened and, therefore,smoothing of the peripheral edges of the coil conductor layers 12 a to12 c is facilitated.

(7) Preferably, the softening temperature of the peripheral glassportion GLB is lower than or equal to the softening temperature of theinternal glass portion GLAi. In this configuration, the coil conductorlayers 12 a to 12 c are formed in the state of being surrounded by theperipheral glass portion GLB that is relatively readily softened and,therefore, smoothing of the peripheral edges of the coil conductorlayers 12 a to 12 c is facilitated.

(8) Preferably, the peripheral glass portion GLB contains at least onetype of filler element, and the peripheral glass GLB has a higher fillerelement concentration than the outlying glass portion. In thisconfiguration, the coil conductor layers 12 a to 12 c are formed in thestate of being surrounded by the peripheral glass portion GLB that isrelatively readily softened and, therefore, smoothing of the peripheraledges of the coil conductor layers 12 a to 12 c is facilitated.

(9) Preferably, the Si concentration in the peripheral glass portion GLBis lower than the Si concentration in the outlying glass portion. Inthis configuration, the coil conductor layers 12 a to 12 c are formed inthe state of being surrounded by the peripheral glass portion GLB thatis relatively readily softened and, therefore, smoothing of theperipheral edges of the coil conductor layers 12 a to 12 c isfacilitated.

(10) Preferably, the Si concentration in the peripheral glass portionGLB is lower than the Si concentration in the outer layer glass portioncontained in the insulator layer 18 serving as the outermost layer. Inthis configuration, the clarity of the portion located at the outermostposition in the element body 11 is improved, the visibility of alignmentmarks 21 is improved, and precision in division into pieces is improved.

(11) The Si concentration in the peripheral glass portion GLB may behigher than the Si concentration in the outer layer glass portion. Inthis configuration, the strength of the element body 11 is enhanced.

(12) Preferably, the average grain size of crystallites of the metalpart M included in each of the coil conductor layers 12 a to 12 c isabout 0.5 μm or more and 15.0 μm or less (i.e., from about 0.5 μm to15.0 μm). In this configuration, grain boundaries that suppress the flowof electrons are decreased. Therefore, the resistance of the coilconductor layer can be reduced, excessive growth of crystallites issuppressed, and smoothing of the peripheral edges of the coil conductorlayers 12 a to 12 c is facilitated.

(13) Preferably, the element body 11 is a sintered body. In thisconfiguration, the strength of the element body 11 is enhanced.

(14) Preferably, the outer surface of the element body 11 includes amounting surface 11 a on which both the first outer electrode 13 x andthe second outer electrode 13 y are disposed, a first end surface 11 bon which only the first outer electrode 13 x is disposed, and a secondend surface 11 c on which only the second outer electrode 13 y isdisposed. In this configuration, mounting solder forms fillets on thefirst end surface 11 b and the second end surface 11 c during mountingof the multilayer inductor component 10 on a substrate, and the fixingforce of the multilayer inductor component 10 to the substrate can beincreased. In this case, it is preferable that the mounting surface 11a, the first end surface 11 b, and the second end surface 11 c beorthogonal to the planes (principal surfaces of the insulating layers)on which the coil conductor layers 12 a to 12 c extend. In thisconfiguration, magnetic fluxes generated in the coil 12 are not readilyblocked by the first outer electrode 13 x and the second outer electrode13 y, and reduction in Q-factor due to eddy current loss can besuppressed.

(15) Preferably, the softening temperature of the peripheral glassportion GLB is lower than or equal to the softening temperature of theglass part GLA (internal glass portion GLAi and exposed glass portionGLAo). In this configuration, the coil conductor layers 12 a to 12 c areformed in the state of being surrounded by the peripheral glass portionGLB that is relatively readily softened and, therefore, smoothing of theperipheral edges of the coil conductor layers 12 a to 12 c isfacilitated.

(16) Preferably, the multilayer inductor component 10 is produced byadopting a manufacturing method including the steps of forming amultilayer body by using an insulating paste containing a glass powderand an conductive paste containing a metal powder and a glass powdersuch that the coil conductor patterns 12 a to 12 c composed of theconductive paste are arranged between a plurality of insulating pastelayers composed of the insulating paste in the multilayer body andfiring the multilayer body so as to sinter the metal powder and theglass powder into the metal part M and the glass part GLA, respectively,wherein in the forming a multilayer body, the glass powder contained inthe conductive paste has a lower softening temperature than the glasspowder contained in the insulating paste, and in the firing of themultilayer body, the glass powder contained in the conductive pasteforms internal glass portions GLAi entirely included into the metal partM and sintered, and the glass powder contained in the conductive pasteforms a peripheral glass portion GLB by pushed outside the metal part Mand sintered. In this method, regarding the coil conductor layers 12 ato 12 c formed by sintering the coil conductor patterns 12 a to 12 c,the surface area is increased and smoothing of the peripheral edges isfacilitated due to the internal glass portions GLAi and the peripheralglass portion GLB formed in the firing of the multilayer body.

The above-described embodiment may be modified as described below.

The metal part M in the coil conductor layers 12 a to 12 c may becomposed of a good conductor, e.g., Cu or Au, other than Ag. Theinsulator layers 15 a, 15 b, 16 a to 16 c, and 18 may be configured tocontain ferrite, resin, or the like instead of glass. That is, theelement body 11 may be a sintered body other than the glass or be otherthan a sintered body. When the element body 11 is a sintered body, thestrength of the element body 11 is enhanced. There is no particularlimitation regarding the plating applied to the outer electrode, and asimple substance or an alloy of Sn, Ni, Ag, Cu, Pd, or Au or amultilayer configuration by combining a plurality of these may beadopted.

The insulator layer 16, and the cavities 17 and the vias 14 in theinsulator layer 16 may be formed by a method other thanphotolithography, for example, pressure bonding of insulating materialsheets, spin coating, or laser processing or drill processing afterapplication of an insulating paste.

Preferably, each of the coil conductor layers 12 a to 12 c has a highaspect ratio t/w that is a ratio of the thickness t to the width w of across section. A high-frequency current mainly passes an inner sidesurface of a winding structure of each of the coil conductor layers 12 ato 12 c because of a skin effect. Therefore, when the thickness t islarge, the electrical resistance against a high-frequency current can bereduced. In addition, when the width w is small, the inner diameterportion of the winding structure of each of the coil conductor layers 12a to 12 c can be relatively increased and the inductance acquisitionefficiency can be improved.

There is no particular limitation regarding the shape of the outerelectrode, and a shape in which the outer electrode is formed on thefirst end surface, four surfaces adjacent to the first end surface, thesecond end surface, and four surfaces adjacent to the second end surfacemay be adopted or a shape in which the outer electrode is formed on onlythe mounting surface may be adopted.

There is no particular limitation regarding the relationship between thestacking direction and the mounting surface, and a configuration inwhich the stacking direction is orthogonal to the mounting surface maybe adopted.

There is no particular limitation regarding the external shape size. Thesize may be, for example, 1005, 0804, 0603, 0402, or the like withreference to the dimension in the longitudinal direction and thedimension in the lateral direction of the mounting surface, or otherratios may be adopted. There is no particular limitation regarding theheight dimension, and the dimension may be the same as the dimension inthe longitudinal direction or dimension in the lateral direction, or thedimension may be different from these.

While some embodiments of the disclosure have been described above, itis to be understood that variations and modifications will be apparentto those skilled in the art without departing from the scope and spiritof the disclosure. The scope of the disclosure, therefore, is to bedetermined solely by the following claims.

What is claimed is:
 1. A multilayer inductor component comprising: anelement body that includes glass; and a coil that includes a pluralityof coil conductor layers that stacked on the glass in the element body,wherein the glass of the element body contains K as an element of theglass, and a concentration of K in the glass of the element body locatedbetween the adjacent two of the plurality of the coil conductor layersis higher than a concentration of K in the glass of the element bodylocated at a central portion of the element body.
 2. The multilayerinductor component according to claim 1, wherein a Si concentration inthe glass of the element body located between the adjacent two of theplurality of the coil conductor layers is lower than a Si concentrationin the glass of the element body located at the central portion of theelement body.
 3. The multilayer inductor component according to claim 1,wherein when the glass of the element body located at an outermostposition in a stacking direction of the plurality of the coil conductorlayer is denoted as an outer layer glass, and the Si concentration inthe glass of the element body located between the adjacent two of theplurality of the coil conductor layers is lower than the Siconcentration in the outer layer glass.
 4. The multilayer inductorcomponent according to claim 1, wherein when the glass of the elementbody located at an outermost position in a stacking direction of theplurality of the coil conductor layer is denoted as an outer layerglass, and the outer layer glass includes a pigment and a filler.
 5. Themultilayer inductor component according to claim 1, wherein theplurality of the coil conductor layers includes a metal part, and themetal part has a plurality of crystallites, and an average grain size ofthe plurality of the crystallites is from 0.5 μm to 15.0 μm.
 6. Themultilayer inductor component according to claim 1, wherein the elementbody is a sintered body.
 7. The multilayer inductor component accordingto claim 1, further comprising: a first outer electrode and a secondouter electrode that are disposed along an outer surface of the elementbody and that are electrically connected to a first end and a second endof the coil, respectively, wherein the outer surface includes a mountingsurface along which both the first outer electrode and the second outerelectrode are disposed, a first end surface along which only the firstouter electrode is disposed, and a second end surface along which onlythe second outer electrode is disposed, and the mounting surface, thefirst end surface, and the second end surface are parallel to a stackingdirection of the plurality of the coil conductor layers.
 8. Themultilayer inductor component according to claim 7, wherein an externalsize is equal to or smaller than 0402 with reference to a dimension in alongitudinal direction of the mounting surface and a dimension in alateral direction of the mounting surface.
 9. The multilayer inductorcomponent according to claim 1, wherein the glass of the element bodycontains at least one element selected from an element group consistingof Bi, Li, Na, K, Mg, Ca, Sr, Ba, Co, Zn, B, Pb, Al, Zr, P, and V, andtotal value of concentrations of the elements included in the elementgroup in the glass of the element body located between the adjacent twoof the plurality of the coil conductor layers is higher than total valueof concentrations of the elements included in the element group in theglass of the element body located at a central portion of the elementbody.
 10. The multilayer inductor component according to claim 1,wherein the plurality of the coil conductor layers includes a metallicelement and Si.
 11. The multilayer inductor component according to claim10, wherein the plurality of the coil conductor layers includes aninternal Si portion that is entirely included in the metallic element,and at least one of the coil conductor layers has a cross sectionorthogonal to an extension direction of the coil conductor layer inwhich the proportion of a total area of the internal Si portion to atotal area of the Si is less than 50%.
 12. The multilayer inductorcomponent according to claim 10, wherein the plurality of the coilconductor layers includes an internal Si portion that is entirelyincluded in the metallic element, and at least one of the coil conductorlayers has a cross section orthogonal to an extension direction of thecoil conductor layer in which the proportion of a total area of theinternal Si portion to a total area of the Si is 50% or more.
 13. Themultilayer inductor component according to claim 10, wherein theplurality of the coil conductor layers includes an internal Si portionthat is entirely included in the metallic element, and at least one ofthe coil conductor layers has a cross section orthogonal to theextension direction of the coil conductor layer in which the proportionof a total area of the internal Si portion to a total area of the Si is100%.
 14. The multilayer inductor component according to claim 10,wherein the plurality of the coil conductor layers includes an internalSi portion that is entirely included in the metallic element, and atleast one of the coil conductor layers has a cross section orthogonal tothe extension direction of the coil conductor layer in which theproportion of a total area of the internal Si portion to a total area ofthe coil conductor layer is from 1.0% to 20.0%.
 15. The multilayerinductor component according to claim 11, wherein the cross section inwhich the proportion of the total area of the internal Si portion to thetotal area of the Si is less than 50% is located at a central portion ofthe longest straight line portion of the coil conductor layer whichlocated at the outermost position in a stacking direction of theplurality of the coil conductor layers.
 16. The multilayer inductorcomponent according to claim 1, wherein portions of the element bodyextend between the coil conductor layers.
 17. A multilayer inductorcomponent comprising: an element body that includes glass; and a coilthat includes a plurality of coil conductor layers that stacked on theglass in the element body, wherein the glass of the element bodycontains Na as an element of the glass, and a concentration of Na in theglass of the element body located between the adjacent two of theplurality of the coil conductor layers is higher than a concentration ofNa in the glass of the element body located at a central portion of theelement body.
 18. A multilayer inductor component comprising: an elementbody that includes glass; and a coil that includes a plurality of coilconductor layers that stacked on the glass in the element body, whereinthe glass of the element body contains Zn as an element of the glass,and a concentration of Zn in the glass of the element body locatedbetween the adjacent two of the plurality of the coil conductor layersis higher than a concentration of Zn in the glass of the element bodylocated at a central portion of the element body.
 19. The multilayerinductor component according to claim 17, wherein portions of theelement body extend between the coil conductor layers.
 20. Themultilayer inductor component according to claim 18, wherein portions ofthe element body extend between the coil conductor layers.